Pompeo visited Manila and gave a commitment to defend the Philippines in the South China Sea. They had been asked for this commitment previously (most publicly in May 2016) but have always been non-commital.
Two minds about this.
Always get worried when the big boys start posturing, usually ends up with the small boys getting whacked. Clearly it will increase tensions.
On the other hand having the Americans finally commit may prevent further Chinese expansion.
I would feel safer if I thought the US President was more mentally stable but then Obama was wishy washy on this and the Chinese just ignored him and expanded their territory. The expression on Duterte's face clearly showed he had got what he wanted.